1. Title of the Invention
The present invention relates to a process for preparing metal nitride powder.
2. Description of Related Art
Metal nitride powders have been prepared by mixing powder of a metal oxide including Al.sub.2 O.sub.3, ZrO.sub.2 or TiO.sub.2 with carbonaceous powder and heating the mixture in a nitrogen atmosphere.
For the conventional process for preparing metal nitride powder, the metal oxide is mixed with the carbonaceous powder in an amount exceeding a stoichiometric amount in order to cause reduction of the metal oxide to a sufficient degree.
However, excess carbonaceous powder should be removed as required. The carbonaceous substance left in a reaction product after the reaction is removed by heating the reaction product at temperatures in the range from 600.degree. C. to 700.degree. C. However, metal nitrides are likely to be oxidized at a relatively low temperature ranging from 600.degree. C. to 700.degree. C. so that, while the amount of oxygen contained in the reaction system would have been reduced during the reaction, the amount of oxygen may be increased at a post-treatment step for removal of carbon, causing the resulting metal nitride to be fully oxidized.